<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        p.box{
            color: red;
        }
    </style>
</head>
<body>
    <p class="box">这是p标签</p>
    <p>pppp</p>
    <div class="box">这是div标签</div>

</body>
</html>